Ambrosina Michelotti graduated in Dentistry (DDS) in 1984; Honorary Degree in Dentistry at the University of Malmo (Sweden) in 2018. Fullprofessor in Orthodontics and Clinical Gnathology. Director of post-graduated School in Orthodontics and Master course on “Orofacial pain and Temporomandibular Disorders” at the University of Naples Federico II. Editorin Chiefof the Orthodontic and Craniofacial Research journal, Associate Editor of the European Journal of Oral Scienceandof the Journal of Oral Rehabilitation, member of the Editorial Board of the European Journal of Orthodontics.



Update of the etiopathogenesis of TMD:

Occlusion has been considered for years as one of the major aetiological factor causing Temporomandibular Disorders (TMD). Nevertheless, at now the associations reported are few, weak and not consistent across the studies. Furthermore the correction of the malocclusion by an orthodontic treatment did not change the risk of developing TMJ sounds. Hence at today, the role of occlusion in the aetiology of TMD has not been clearly addressed and therefore it should not be overstated, also considering that in some cases occlusal changes could be the consequence rather than a cause for TMDs. Alterations in the temporomandibular joint (TMJ), including congenital developmental (i.e. aplasia, hypo ⁄ hyperplasia), acquired (i.e. neoplasms) and inflammatory (i.e. systemic arthritides, rheumatoid arthritis) disorders, can cause occlusal changes. Indeed the board concept of occlusion has to be expanded from the only peripheral input, referring mainly to how the anatomical and central adaptability react to this stimulus. Hence patients’ individual adaptability has to be taken into account by clinicians to prevent iatrogenic maladaptive behaviours.A

TMD and orthodontics:

It is mandatory to start by taking a thorough history and a comprehensive TMD examination, screening biobehavioral evaluation, assess pain intensity, interference in function from pain, and distress. Diagnoses can be made according to validated criteria and important psychosocial attributes are obtained from the biobehavioural evaluation. If the patient’s chief complaint is pain, the first step is to make a differential diagnosis to determine whether the pain is due to a painful TMD, or due to another disease. The second step is to resolve the pain by following a symptom-focused and behavioural treatment protocol. As a rule, restorative or orthodontic treatment should not be initiated as long as a patient suffers from facial pain. If the patient’s chief complaint is a joint disease, the first step is to make a differential diagnosis in order to determine whether it is a disc displacement, a degenerative joint disease, or a subluxation. The second step depends on the specific diagnosis.

At the beginning of dental treatment with a patient without TMD, the patient should be informed that because TMD characteristics are highly prevalent in the general population and the aetiology is multifactorial, it is not possible to establish any causal association between potential onset and dental therapy. If the patient subsequently presents signs or symptoms of TMD during active dental treatment, the first step is always to evaluate, as previously described, and make the differential diagnosis. The second step is to stop active dental treatment temporarily. The third step is to resolve the pain by following a symptom-focused and behavioural treatment approach. Afterwards, when the patient is pain-free (or when the pain is reliably managed), dental treatment can be continued as previously planned or, if necessary, modified according to the patient’s condition and management.



  1.  Tinastepe N, Oral K. Investigation of the Relationship between Increased Vertical Overlap with Minimum Horizontal Overlap and the Signs of Temporomandibular Disorders. J Prosthodont. 2015;24(6):463-468. doi:10.1111/jopr.12249
  2.  Wang C, Yin X. Occlusal risk factors associated with temporomandibular disorders in young adults with normal occlusions. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012;114(4):419-423. doi:10.1016/j.oooo.2011.10.039
  3. Manfredini D, Lombardo L, Siciliani G. Temporomandibular disorders and dental occlusion. A systematic review of association studies: end of an era? J Oral Rehabil. 2017;44(11):908-923. doi:10.1111/joor.12531
  4. John MT, Hirsch C, Drangsholt MT, Mancl LA, Setz JM.Overbite and overjet are not related to self-report of temporomandibular disorder symptoms. J Dent Res. 2002;81(3):164-169.
  5. Hirsch C, John MT, Drangsholt MT, Mancl LA. Relationship between overbite/overjet and clicking or crepitus of the temporomandibular joint. J Orofac Pain. 2005;19(3):218-225.
  6. Iodice G, Cimino R, Vollaro S, Lobbezoo F, Michelotti A. Prevalence of temporomandibular disorder pain, jaw noises and oral behaviours in an adult Italian population sample. J Oral Rehabil. 2019;46(8):691-698. doi:10.1111/joor.12803
  7. Iodice G, Danzi G, Cimino R, Paduano S, Michelotti A. Association between posterior crossbite, masticatory muscle pain, and disc displacement: a systematic review. Eur J Orthod. 2013;35(6):737-744. doi:10.1093/ejo/cjt024
  8. Iodice G, Danzi G, Cimino R, Paduano S, Michelotti A. Association between posterior crossbite, skeletal, and muscle asymmetry: a systematic review. Eur J Orthod. 2016;38(6):638-651. doi:10.1093/ejo/cjw003
  9. Farella M, Michelotti A, Iodice G, Milani S, Martina R. Unilateral posterior crossbite is not associated with TMJ clicking in young adolescents. J Dent Res. 2007;86(2):137-141. doi:10.1177/154405910708600206
  10. Michelotti A, Iodice G, Piergentili M, FarellaM, Martina R. Incidence of temporomandibular joint clicking in adolescents with and without unilateral posterior cross-bite: a 10-year follow-up study. J Oral Rehabil. 2016;43(1):16-22. doi:10.1111/joor.12337
  11. Forssell H, Kalso E. Application of principles of evidence-based medicine to occlusal treatment for temporomandibular disorders: are there lessons to be learned? J Orofac Pain. 2004;18(1):9-22.
  12. Schiffman E, Ohrbach R, Truelove E, Look J, An-derson G, Goulet J-P, et al. Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for Clinical and Research Applications: Recommendations of the International RDC/TMD Consortium Network and Orofacial Pain Special Interest Group. Journal of Oral & Facial Pain and Headache. 2014;28(1):6-27.
  13. Ohrbach R, Bair E, Fillingim RB, Gonzalez Y, Gordon SM, Lim PF, et al. Clinical orofacial characteristics associated with risk of first-onset TMD: the OPPERA prospective cohort study. Journal of Pain. 2013;14 (Supplement 2)(12):T33-T50.
  14. Mobilio N, Catapano S. Effect of experimental jaw muscle pain on occlusal contacts. Journal of Oral Rehabilitation. 2011;38(6):404-9.
    Michelotti A, Iodice G, Vollaro S, Steenks MH, Farella M. Evaluation of the short-term effectiveness of education versus an occlusal splint for the treatment of myofascial pain of the jaw muscles. J Am Dent Assoc. 2012 Jan;143(1):47-53.
  15. Cairns B, List T, Michelotti A, Ohrbach R, Svensson P. JOR-CORE recommendations on rehabilitation of temporomandibular disorders. J Oral Rehabil. 2010 May;37(6):481-9. 
  16. Michelotti A, Iodice G. The role of orthodontics in temporomandibular disorders. J Oral Rehabil. 2010 May;37(6):411-29. Epub 2010 Apr 9. Review. 
  17. Michelotti A, Steenks MH, Farella M, ParisiniF, Cimino R, Martina R. The additional value of a home physical therapy regimen versus patient education only for the treatment of my-ofascial pain of the jaw muscles: Short-term results of a randomized clinical trial. J Orofac Pain 2004;18:114-125.
  18. MichelottiA,deWijerA,SteenksM,FarellaM.Home-exercise regimes for the managementof non-specific temporomandibular disorders. J Oral Rehabil 2005;32:779–785.
  19. Armijo-Olivo S, Pitance L, Singh V, Neto F, Thie N, Michelotti A. Effectiveness of manual therapy and therapeutic exercise for temporomandibular disorder: Systematic review and meta-analysis. Phys Ther 2016;96:9–25.